Ventilator units already exist for ventilating garments such as pressure suits or the like with an ambient fluid, however they do not all satisfy operating conditions in the above-mentioned applications, or else they are of a structure that is not sufficiently compact to enable them to be made completely self-contained and easy to manufacture and to associate with the garments they are to ventilate, nor are they sufficiently simple to ensure that the operations required for maintenance are relatively easy.